Adverse Drug Reactions Associated with Cancer Immunotherapy: Mechanisms, Clinical Spectrum, and Management Strategies

Cancer immunotherapy has substantially reshaped contemporary oncology by improving survival outcomes across solid tumours and haematological malignancies. Immune Checkpoint Inhibitors (ICIs) and Chimeric Antigen Receptor T-cell (CAR-T) therapies enhance antitumor immune activity but are associated with a distinctive spectrum of immune-mediated adverse drug reactions, collectively termed immune-Related Adverse Events (irAEs). These toxicities may involve virtually any organ system and range from mild, self-limiting manifestations to severe, life-threatening complications requiring aggressive immunosuppression. This review provides a structured synthesis of the mechanisms, clinical manifestations, grading systems, and evidence-based management strategies for immunotherapy-associated adverse reactions, with particular emphasis on ICIs and CAR-T therapies. Updated international consensus recommendations are incorporated to support standardized clinical practice. Structured pharmacovigilance frameworks and multidisciplinary collaboration-including formal integration of clinical pharmacists-are emphasized as critical components to improve early detection, optimize toxicity management, and enhance patient safety outcomes.